How to update nested Records?

Not best practice: Create an opaque type instead.
Problem
Solution
Alternative Solution
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type alias Movie = 
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    { title : String
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    , rating : Int
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    }
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type alias Model = 
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    { currentMovie : Movie
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    }
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​
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rate : Int -> Model -> Model
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rate newRating model =
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    { model 
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    | currentMovie = 
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        --{ model.currentMovie | rating = newRating }
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        Debug.todo "the line above does not compile"
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    }
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type alias Movie = 
2
    { title : String
3
    , rating : Int
4
    }
5
  
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type alias Model = 
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    { currentMovie : Movie
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    }
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​
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rate : Int -> Model -> Model
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rate newRating ({currentMovie} as model) =
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    { model 
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    | currentMovie = 
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        {currentMovie | rating = newRating }
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    }
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1
type alias Movie = 
2
    { title : String
3
    , rating : Int
4
    }
5
  
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type alias Model = 
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    { currentMovie : Movie
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    }
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​
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rate : Int -> Model -> Model
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rate rating ({currentMovie} as model) =
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    model
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    |> updateMovie (addRating rating)
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​
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updateMovie : (Movie -> Movie) -> Model -> Model
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updateMovie fun ({currentMovie} as model) =
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    { model | currentMovie = fun currentMovie}
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addRating : Int -> Movie -> Movie
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addRating rating movie =
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    { movie | rating = rating}
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This is the a better solution
Question
How can I update a nested record field?
Answer
First get the nested record, then update it:
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let
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    currentMovie = model.currentMovie
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in
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{ currentMovie | rating = newRating}
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For function parameters we can use the keyword as to bind fields of a record to a variable with the same name:
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rate newRating ({currentMovie} as model) =
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    ...
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Further reading
📄Article: Updating nested records in Elm by Wouter In t Velt

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